Features of waves

Home learning focus

Learn more about the features of waves in today's lesson.

This guide contains:

  • two videos
  • three activities to reinforce learning.

Learn

Waves cause a disturbance of the medium through which they travel, which allows them to carry energy.

Watch the video below to learn more about the characteristics of waves.

The characteristics of waves and how they transfer energy from one point to another.

Features of waves

Sine wave showing peaks, troughs and wavelength

Amplitude

The amplitude (a) of a wave is the distance from the centre line (or the still position) to the top of a crest or to the bottom of a trough. Be careful with this quantity - the centre line is not always given in a diagram. Amplitude is measured in metres (m). The greater the amplitude of a wave then the more energy it is carrying.

Wavelength

The wavelength, /lambda, of a wave is the distance from any point on one wave to the same point on the next wave along. (The symbol is a Greek letter, 'lambda'.) To avoid confusion, it is best to measure wavelength from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough. Wavelength is also measured in metres (m) - it is a length after all.

Frequency

The frequency (f) of a wave is the number of waves passing a point in a certain time. We normally use a time of one second, so this gives frequency the unit hertz (Hz), since one hertz is equal to one wave per second.

Don't get confused with this quantity frequency. It is not a distance travelled by waves, nor is it a speed, although it is linked to both of these quantities. For water waves and sound waves the unit hertz is usually good enough but radio and TV waves have such a high frequency that the kilohertz (kHz) or even the megahertz (MHz) are better units.

1kHz = 1,000Hz

1MHz = 1,000,000Hz

Speed

The speed (or sometimes you might see it called velocity) of a wave (v) is how far the wave travels in a certain time.

Wave speed is measured in metres per second (m s ⁻¹)

All the electromagnetic waves travel at 300,000,000 metres per second (3 x 10⁸ m s⁻¹).

Sound travels at about 340 metres per second.

Sound waves

Practise

There are lots of ways to try out your science skills.

Activity 1

Check your understanding of waves with this dominoes game from Teachitscience

Print the dominoes out, cut along the dotted lines and use your knowledge to match the dominoes together.

If you are unable to print the dominoes, you can grab a pen and paper to write your answers out!

Waves Dominoes

Activity 2

Test your knowledge with this quiz!

Activity 3

Write down five sounds you can hear. Estimate the amplitude (loudness) and frequency (pitch) on a scale of 1 - 10.

1 being low and 10 being high.

There's more to learn

Have a look at these other resources around the BBC and the web.

More lessons for Year 8 and S2
KS3 Physics
KS3 Physics
Check out video content on iPlayer